Synergetic pore structure optimization and nitrogen doping of 3D porous graphene for high performance lithium sulfur battery

Abstract

Synthesis of multifunctional sulfur host material with comprehensive abilities of sulfur accommodation, electron/ion transfer and polysulfides confining is vital and challenging to bring the theoretical merits of lithium sulfur battery to practical application. Herein, a facile strategy is demonstrated to prepare 3-dimensional hierarchical porous nitrogen doped graphene as a sulfur host material for lithium sulfur battery, where urea is employed as both nitrogen doping source and self-removed template for pore structure optimization. The resultant material possesses high nitrogen doping content, 3-dimentional interconnected hierarchical porosity and conductive network and robust mechanical structure, which give rise to a comprehensive ability for multiscale electron/ion transfer, sulfur accommodation and polysulfides confining. Benefiting from the rational structure design, the sulfur loaded composite exhibits high sulfur utilization (1311 mA h g−1 at 0.2 C), high rate capability (950, 762 and 580 mA h g−1 at 1, 2 and 3 C respectively) and excellent cycling stability with high sulfur mass loading (714 mA h g−1 at 1.5 mA cm−2 after 400 cycles for a sulfur loading of 4 mg cm−2). The outstanding electrochemical performance, scalable fabrication process, and compatibility with industrial slurry-coating process makes it an ideal host material for practical application of lithium sulfur battery.